Many electronic devices, such as portable electronic devices, include power packs such as batteries to provide operating power to the device. Batteries store an amount of electrical charge and discharge as electrical current is drained from the battery. Some devices include a capacity monitor that maintains an estimate of the remaining capacity in the battery providing power to a device. The capacity monitors often produce an indicator when a discharging battery reaches certain remaining capacity levels. These indicators are used for various purposes, such as providing an indication to a user that the remaining capacity level in the battery is low and will be soon depleted. Once a user receives that warning, a user may stop using the device for unnecessary tasks or power down the device. A controller within the device may also react to low or nearly depleted remaining capacity state indicators by automatically altering circuit configurations or modes, or by powering down some or all electrical circuits as the battery nears a depleted remaining capacity level.
Remaining capacity monitors often operate my monitoring a net amount of electrical current that is provided to or drained from the battery. One dedicated circuit that performs this monitoring is referred to as a “Coulomb counting fuel gauge.”Coulomb counter fuel gauges operate by integrating electrical current that is provided to and drained from the battery. Electrical current is provided to the battery by, for example, a charging circuit. Electrical current is drained from the battery by a load, such as an operating circuit. Various factors operate to alter the characteristics of a battery or otherwise cause the Coulomb counting technique of battery capacity monitoring to be inaccurate. Such inaccuracies, particularly at high battery temperatures, sometimes result in a battery reaching a depleted remaining capacity state before the monitoring circuits provide an indication of the depleted state.
Therefore, the operation of battery powered devices will benefit from improved accuracies in detecting low remaining capacity and depleted remaining capacity states of a battery.